Temperature indicating instrument



March 18, 1941. R. l. BRADLEY TEMPERATURE INDICATING INSTRUMENT FiledDec. 6, 1938 Patented Mar. 18, 1941 UNITED STATES.

TEMPERATURE INDICATING INSTRUMENT Robert I. Bradley, Belmont, Mass.

Application December 6, 1938, Serial No. 244,202

1 Claim.

This invention relates to temperature-indicating instruments, such asthermometers, and more particularly to thermometers wherein thetemperature-determining means is any suitable, preferablylinearly-expansive, element or elements, and so mounted that itssupporting means or base is particularly adapted to be secured to awindow pane, for instance, the window of an automobile, or house, andthe expansion element and graduations thereon legible through thewindow, and if desired, also, through the thermometer base itself.

Of the embodiment of my invention selected for illustration anddescription, herein:

Fig. 1 is a front elevation, or, when mounted, an inner face View, on anenlarged scale for convenience, as are also all the figures;

Fig. 2, a vertical section on the line 22, Fig. 1, looking in thedirection of the arrow;

Fig. 3 shows a modified form of construction, with a cover for the basemember;

Fig. 4, a view similar to Fig. 1, embodying a modified construction oftemperature-determining means;

Fig. 5, a sectional view on the line 5-5, Fig. 4;

Fig. 6, a side elevation, or edge view, partly broken away, of thecomposite metal, expansive element.

My novel thermometer, Figs. 1, 2, comprises a base, as a disk I, of anymaterial; as glass, Celluloid or the like, and plain or colored, and ofany outline, but preferably circular, and, for convenience, dish-shapedor curvilinear in cross section, and of any convenient size, as threeinches in diameter, or more or less if desired.

The inner surface edge 2 of the disk may be ground to ensure that itwill cooperate with any suitable cement to provide a tight joint with atransparent pane, as of glass 3, Fig. 5, as in a window, or with atransparent back or cover member 4, as glass, Celluloid or the like,Fig. 3, if it is desired to use the cover member, and with or without asuitable gasket.

The inner surface of the disk, preferably near its circumferential edge,Fig. 1, is provided in any convenient manner with short dashes, ormeasuring graduations 5, of suitable color, indicating degrees oftemperature from 1 F., or any number above or below it, in this casefrom below F.,

0 to any higher number that is within the contemplated range of use ofthe instrument, as 110 F., the graduations bein accompanied at intervalsby numbers, or other identifying indicia 6, of a suitable color forconvenience, painted on or otherwise applied to the disk.

On a stud or other support I, Figs. 1, 2, at the center of the disk, andcemented or otherwise conveniently secured thereto, is secured one endof a curvilinear, expansive thermo coil member 8. In the presentinstance, Fig. 1 this member 8 5 has one end positioned in a slot 9 inthe stud, the walls of the slot being compressed tightly against theend.

This thermo coil member, 8, should be of a material that has a knownconstant ratio, or coeffil0 cient expansion and contraction, as metal,or preferably, as in the present case, Fig. 6, of two or more metals,which cooperate to produce a dependable constant ratio or coefl'lcientof expansion and contraction, and are therefore reliable exponents ofthe temperature changes.

The outer end I0 of the expansible coil 8 is bent at, a sharp angle,Fig. l, and twisted approximately at 180 to form an arrow-shapedpointer,

Illa.

In the present case, Fig. 6, the coil member is composed of two metals,as brass and elvinar, and the two thin strips of said metals arecompressed, face to face, and fused together.

If the disk is to be mounted upon a transparent as back 4, Fig. 3, thedisk is cemented, or otherwise satisfactorily secured around the diskedge thereto by any suitable cement, as cellulose acetate in nature, andthe back 4 thereafter suitably mounted upon a glass window, Fig. 3, asby the same or similar cement. Otherwise, the disk I itself is cemented,Fig. 5, directly to the window. A cement commercially known as No. 4713is satisfactory for this purpose.

For convenience, the inner edge of the disk I may have a strip of said,or otherwise suitable, cement I9 applied thereto, Fig. 2, and permittedto dry. When the disk is to be cemented to the window, the cement issoftened by the use of any suitable solvent or thinner, as onecommercially 40 identified as No. 3120.

The graduations of the scale 5 are properly calibrated to an acceptedstandard, so that the pointer Illa, as it travels over the scale, willcorrectly indicate the temperature outside of the disk, suitableallowance being made for the presence of the disk I, whether the disk isprovided with the base 4, or mounted directly upon a window 3.

In Figs. 4, 5, I have shown a modified form of construction, wherein thepointer I 2 is formed as a separate member and inserted through anaperture I3 in the coil outer end. The pointer inner end is pivoted orotherwise fastened to the stud I to rotate thereon. The end of the lastturn of ber, a temperature responsive coil secured at one end to theconcave face of the base member, a pointer actuated by the opposite endof said coil, temperature graduations on the base member along which thepointer moves, the rim of the 5 base member being adapted to engageagainst a fiat transparent sheet of material whereby a chamber isformed, the concavity of the base member being of such depth to housethe temperature indicating mechanism within the cham- 10 her.

ROBERT I. BRADLEY.

